1. Field of the Invention
The present invention generally involves the field of technology pertaining to resilient foundations, such as beds, chaise lounge cushions or the like, specifically designed for supporting the human body in a prone position of sleep or rest. More specifically, the invention relates to an improved device for varying the firmness of a resilient foundation, particularly a box spring on which a mattress may be disposed for defining a bed assembly.
2. Description of the Prior Art
A conventional bed assembly is basically defined by a foundation on which an overlying mattress is supported. The foundation may comprise a rigid frame assembly which, in combination with a resilient mattress, forms what is known in the industry as a platform bed. More traditionally, the foundation is provided with a plurality of spaced internal coil springs which afford a certain degree of resilient support for the overlying mattress. The firmness experienced by the user in traditional beds must necessarily be limited to the inherent firmness of the mattress and foundation. This situation constrains the user to an established degree of firmness which can only be varied by substituting the existing mattress or foundation with another having the desired firmness. Another problem arises in those situations wherein a couple share the same bed and, because of different body weights or different firmness preferences, it is often necessary for the couple to compromise their individual comfort needs.
The prior art has recognized the aforediscussed problems associated with conventional bed structures and has attempted to overcome these problems by providing various approaches through which the firmness of either the foundation or mattress may be selectively varied. These proposals basically involve mechanisms for varying the inherent resiliency of the existing resilient support structure of the foundation or mattress. For example, it is well known to compress the individual coil springs of a foundation in order to limit their degree of compression, thereby modifying the inherent resiliency of the springs. Examples of this and other similar forms of known firmness control mechanisms are disclosed by the Robell U.S. Pat. No. 2,504,352, Backus U.S. Pat. No. 2,558,288, Bloom U.S. Pat. No. 2,985,895, Cunningham U.S. Pat. No. 3,166,768, Frye U.S. Pat. No. 3,252,170, Frye U.S. Pat. No. 3,551,924, Sproll U.S. Pat. No. 3,553,745, Johnson U.S. Pat. No. 3,739,409, and Usami U.S. Pat. No. 4,222,137.